/**************************************************************************/
/*  hashfuncs.h                                                           */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
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/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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/* a copy of this software and associated documentation files (the        */
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#ifndef HASHFUNCS_H
#define HASHFUNCS_H

#include "backend/text_server/config.h"
#include "backend/text_server/ustring.h"
#include "backend/text_server/rid.h"
#include "backend/text_server/rect2.h"
#include "backend/text_server/vector2.h"
#include "backend/text_server/vector3.h"
#include "backend/text_server/string_name.h"

#include <cmath>

namespace godot
{

/**
 * Hashing functions
 */

/**
 * DJB2 Hash function
 * @param C String
 * @return 32-bits hashcode
 */
static _FORCE_INLINE_ uint32_t hash_djb2(const char* p_cstr)
{
    const unsigned char* chr = (const unsigned char*)p_cstr;
    uint32_t             hash = 5381;
    uint32_t             c = *chr++;

    while (c)
    {
        hash = ((hash << 5) + hash) ^ c; /* hash * 33 ^ c */
        c = *chr++;
    }

    return hash;
}

static _FORCE_INLINE_ uint32_t hash_djb2_buffer(const uint8_t* p_buff, int p_len, uint32_t p_prev = 5381)
{
    uint32_t hash = p_prev;

    for (int i = 0; i < p_len; i++)
    {
        hash = ((hash << 5) + hash) ^ p_buff[i]; /* hash * 33 + c */
    }

    return hash;
}

static _FORCE_INLINE_ uint32_t hash_djb2_one_32(uint32_t p_in, uint32_t p_prev = 5381)
{
    return ((p_prev << 5) + p_prev) ^ p_in;
}

/**
 * Thomas Wang's 64-bit to 32-bit Hash function:
 * https://web.archive.org/web/20071223173210/https:/www.concentric.net/~Ttwang/tech/inthash.htm
 *
 * @param p_int - 64-bit unsigned integer key to be hashed
 * @return unsigned 32-bit value representing hashcode
 */
static _FORCE_INLINE_ uint32_t hash_one_uint64(const uint64_t p_int)
{
    uint64_t v = p_int;
    v = (~v) + (v << 18); // v = (v << 18) - v - 1;
    v = v ^ (v >> 31);
    v = v * 21; // v = (v + (v << 2)) + (v << 4);
    v = v ^ (v >> 11);
    v = v + (v << 6);
    v = v ^ (v >> 22);
    return uint32_t(v);
}

#define HASH_MURMUR3_SEED 0x7F07C65
// Murmurhash3 32-bit version.
// All MurmurHash versions are public domain software, and the author disclaims all copyright to their code.

static _FORCE_INLINE_ uint32_t hash_murmur3_one_32(uint32_t p_in, uint32_t p_seed = HASH_MURMUR3_SEED)
{
    p_in *= 0xcc9e2d51;
    p_in = (p_in << 15) | (p_in >> 17);
    p_in *= 0x1b873593;

    p_seed ^= p_in;
    p_seed = (p_seed << 13) | (p_seed >> 19);
    p_seed = p_seed * 5 + 0xe6546b64;

    return p_seed;
}

static _FORCE_INLINE_ uint32_t hash_murmur3_one_float(float p_in, uint32_t p_seed = HASH_MURMUR3_SEED)
{
    union
    {
        float    f;
        uint32_t i;
    } u;

    // Normalize +/- 0.0 and NaN values so they hash the same.
    if (p_in == 0.0f)
    {
        u.f = 0.0;
    }
    else if (::isnan(p_in))
    {
        u.f = NAN;
    }
    else
    {
        u.f = p_in;
    }

    return hash_murmur3_one_32(u.i, p_seed);
}

static _FORCE_INLINE_ uint32_t hash_murmur3_one_64(uint64_t p_in, uint32_t p_seed = HASH_MURMUR3_SEED)
{
    p_seed = hash_murmur3_one_32(p_in & 0xFFFFFFFF, p_seed);
    return hash_murmur3_one_32(p_in >> 32, p_seed);
}

static _FORCE_INLINE_ uint32_t hash_murmur3_one_double(double p_in, uint32_t p_seed = HASH_MURMUR3_SEED)
{
    union
    {
        double   d;
        uint64_t i;
    } u;

    // Normalize +/- 0.0 and NaN values so they hash the same.
    if (p_in == 0.0f)
    {
        u.d = 0.0;
    }
    else if (::isnan(p_in))
    {
        u.d = NAN;
    }
    else
    {
        u.d = p_in;
    }

    return hash_murmur3_one_64(u.i, p_seed);
}

static _FORCE_INLINE_ uint32_t hash_murmur3_one_real(real_t p_in, uint32_t p_seed = HASH_MURMUR3_SEED)
{
#ifdef REAL_T_IS_DOUBLE
    return hash_murmur3_one_double(p_in, p_seed);
#else
    return hash_murmur3_one_float(p_in, p_seed);
#endif
}

static _FORCE_INLINE_ uint32_t hash_rotl32(uint32_t x, int8_t r)
{
    return (x << r) | (x >> (32 - r));
}

static _FORCE_INLINE_ uint32_t hash_fmix32(uint32_t h)
{
    h ^= h >> 16;
    h *= 0x85ebca6b;
    h ^= h >> 13;
    h *= 0xc2b2ae35;
    h ^= h >> 16;

    return h;
}

static _FORCE_INLINE_ uint32_t hash_murmur3_buffer(const void* key, int length, const uint32_t seed = HASH_MURMUR3_SEED)
{
    // Although not required, this is a random prime number.
    const uint8_t* data = (const uint8_t*)key;
    const int      nblocks = length / 4;

    uint32_t h1 = seed;

    const uint32_t c1 = 0xcc9e2d51;
    const uint32_t c2 = 0x1b873593;

    const uint32_t* blocks = (const uint32_t*)(data + nblocks * 4);

    for (int i = -nblocks; i; i++)
    {
        uint32_t k1 = blocks[i];

        k1 *= c1;
        k1 = hash_rotl32(k1, 15);
        k1 *= c2;

        h1 ^= k1;
        h1 = hash_rotl32(h1, 13);
        h1 = h1 * 5 + 0xe6546b64;
    }

    const uint8_t* tail = (const uint8_t*)(data + nblocks * 4);

    uint32_t k1 = 0;

    switch (length & 3)
    {
        case 3:
            k1 ^= tail[2] << 16;
            [[fallthrough]];
        case 2:
            k1 ^= tail[1] << 8;
            [[fallthrough]];
        case 1:
            k1 ^= tail[0];
            k1 *= c1;
            k1 = hash_rotl32(k1, 15);
            k1 *= c2;
            h1 ^= k1;
    };

    // Finalize with additional bit mixing.
    h1 ^= length;
    return hash_fmix32(h1);
}

static _FORCE_INLINE_ uint32_t hash_djb2_one_float(double p_in, uint32_t p_prev = 5381)
{
    union
    {
        double   d;
        uint64_t i;
    } u;

    // Normalize +/- 0.0 and NaN values so they hash the same.
    if (p_in == 0.0f)
    {
        u.d = 0.0;
    }
    else if (::isnan(p_in))
    {
        u.d = NAN;
    }
    else
    {
        u.d = p_in;
    }

    return ((p_prev << 5) + p_prev) + hash_one_uint64(u.i);
}

template <class T>
static _FORCE_INLINE_ uint32_t hash_make_uint32_t(T p_in)
{
    union
    {
        T        t;
        uint32_t _u32;
    } _u;
    _u._u32 = 0;
    _u.t = p_in;
    return _u._u32;
}

static _FORCE_INLINE_ uint64_t hash_djb2_one_float_64(double p_in, uint64_t p_prev = 5381)
{
    union
    {
        double   d;
        uint64_t i;
    } u;

    // Normalize +/- 0.0 and NaN values so they hash the same.
    if (p_in == 0.0f)
    {
        u.d = 0.0;
    }
    else if (::isnan(p_in))
    {
        u.d = NAN;
    }
    else
    {
        u.d = p_in;
    }

    return ((p_prev << 5) + p_prev) + u.i;
}

static _FORCE_INLINE_ uint64_t hash_djb2_one_64(uint64_t p_in, uint64_t p_prev = 5381)
{
    return ((p_prev << 5) + p_prev) ^ p_in;
}

template <class T>
static _FORCE_INLINE_ uint64_t hash_make_uint64_t(T p_in)
{
    union
    {
        T        t;
        uint64_t _u64;
    } _u;
    _u._u64 = 0; // in case p_in is smaller

    _u.t = p_in;
    return _u._u64;
}

struct HashMapHasherDefault {
    // Generic hash function for any type.
    template <class T>
    static _FORCE_INLINE_ uint32_t hash(const T* p_pointer) { return hash_one_uint64((uint64_t)p_pointer); }

    template <class T>
    static _FORCE_INLINE_ uint32_t hash(const Ref<T>& p_ref) { return hash_one_uint64((uint64_t)p_ref.operator->()); }

    static _FORCE_INLINE_ uint32_t hash(const String& p_string) { return p_string.hash(); }
    static _FORCE_INLINE_ uint32_t hash(const char* p_cstr) { return hash_djb2(p_cstr); }
    static _FORCE_INLINE_ uint32_t hash(const wchar_t p_wchar) { return hash_fmix32(p_wchar); }
    static _FORCE_INLINE_ uint32_t hash(const char16_t p_uchar) { return hash_fmix32(p_uchar); }
    static _FORCE_INLINE_ uint32_t hash(const char32_t p_uchar) { return hash_fmix32(p_uchar); }
    static _FORCE_INLINE_ uint32_t hash(const RID& p_rid) { return hash_one_uint64(p_rid.get_id()); }
    static _FORCE_INLINE_ uint32_t hash(const CharString& p_char_string) { return hash_djb2(p_char_string.ptr()); }
    static _FORCE_INLINE_ uint32_t hash(const StringName& p_string_name) { return p_string_name.hash(); }
    // static _FORCE_INLINE_ uint32_t hash(const NodePath &p_path) { return p_path.hash(); }
    // static _FORCE_INLINE_ uint32_t hash(const ObjectID &p_id) { return hash_one_uint64(p_id); }

    static _FORCE_INLINE_ uint32_t hash(const uint64_t p_int) { return hash_one_uint64(p_int); }
    static _FORCE_INLINE_ uint32_t hash(const int64_t p_int) { return hash_one_uint64(p_int); }
    static _FORCE_INLINE_ uint32_t hash(const float p_float) { return hash_murmur3_one_float(p_float); }
    static _FORCE_INLINE_ uint32_t hash(const double p_double) { return hash_murmur3_one_double(p_double); }
    static _FORCE_INLINE_ uint32_t hash(const uint32_t p_int) { return hash_fmix32(p_int); }
    static _FORCE_INLINE_ uint32_t hash(const int32_t p_int) { return hash_fmix32(p_int); }
    static _FORCE_INLINE_ uint32_t hash(const uint16_t p_int) { return hash_fmix32(p_int); }
    static _FORCE_INLINE_ uint32_t hash(const int16_t p_int) { return hash_fmix32(p_int); }
    static _FORCE_INLINE_ uint32_t hash(const uint8_t p_int) { return hash_fmix32(p_int); }
    static _FORCE_INLINE_ uint32_t hash(const int8_t p_int) { return hash_fmix32(p_int); }
    static _FORCE_INLINE_ uint32_t hash(const Vector2i& p_vec)
    {
        uint32_t h = hash_murmur3_one_32(p_vec.x);
        h = hash_murmur3_one_32(p_vec.y, h);
        return hash_fmix32(h);
    }
    static _FORCE_INLINE_ uint32_t hash(const Vector3i& p_vec)
    {
        uint32_t h = hash_murmur3_one_32(p_vec.x);
        h = hash_murmur3_one_32(p_vec.y, h);
        h = hash_murmur3_one_32(p_vec.z, h);
        return hash_fmix32(h);
    }
    /*
    static _FORCE_INLINE_ uint32_t hash(const Vector4i &p_vec) {
        uint32_t h = hash_murmur3_one_32(p_vec.x);
        h = hash_murmur3_one_32(p_vec.y, h);
        h = hash_murmur3_one_32(p_vec.z, h);
        h = hash_murmur3_one_32(p_vec.w, h);
        return hash_fmix32(h);
    }
    */
    static _FORCE_INLINE_ uint32_t hash(const Vector2& p_vec)
    {
        uint32_t h = hash_murmur3_one_real(p_vec.x);
        h = hash_murmur3_one_real(p_vec.y, h);
        return hash_fmix32(h);
    }
    static _FORCE_INLINE_ uint32_t hash(const Vector3& p_vec)
    {
        uint32_t h = hash_murmur3_one_real(p_vec.x);
        h = hash_murmur3_one_real(p_vec.y, h);
        h = hash_murmur3_one_real(p_vec.z, h);
        return hash_fmix32(h);
    }
    static _FORCE_INLINE_ uint32_t hash(const Rect2& p_rect)
    {
        uint32_t h = hash_murmur3_one_real(p_rect.position.x);
        h = hash_murmur3_one_real(p_rect.position.y, h);
        h = hash_murmur3_one_real(p_rect.size.x, h);
        h = hash_murmur3_one_real(p_rect.size.y, h);
        return hash_fmix32(h);
    }
    /*
    static _FORCE_INLINE_ uint32_t hash(const Rect2i &p_rect) {
        uint32_t h = hash_murmur3_one_32(p_rect.position.x);
        h = hash_murmur3_one_32(p_rect.position.y, h);
        h = hash_murmur3_one_32(p_rect.size.x, h);
        h = hash_murmur3_one_32(p_rect.size.y, h);
        return hash_fmix32(h);
    }
    static _FORCE_INLINE_ uint32_t hash(const Vector4 &p_vec) {
        uint32_t h = hash_murmur3_one_real(p_vec.x);
        h = hash_murmur3_one_real(p_vec.y, h);
        h = hash_murmur3_one_real(p_vec.z, h);
        h = hash_murmur3_one_real(p_vec.w, h);
        return hash_fmix32(h);
    }
    static _FORCE_INLINE_ uint32_t hash(const AABB &p_aabb) {
        uint32_t h = hash_murmur3_one_real(p_aabb.position.x);
        h = hash_murmur3_one_real(p_aabb.position.y, h);
        h = hash_murmur3_one_real(p_aabb.position.z, h);
        h = hash_murmur3_one_real(p_aabb.size.x, h);
        h = hash_murmur3_one_real(p_aabb.size.y, h);
        h = hash_murmur3_one_real(p_aabb.size.z, h);
        return hash_fmix32(h);
    }
    */
};

template <typename T>
struct HashMapComparatorDefault {
    static bool compare(const T& p_lhs, const T& p_rhs)
    {
        return p_lhs == p_rhs;
    }
};

template <>
struct HashMapComparatorDefault<float> {
    static bool compare(const float& p_lhs, const float& p_rhs)
    {
        return (p_lhs == p_rhs) || (::isnan(p_lhs) && ::isnan(p_rhs));
    }
};

template <>
struct HashMapComparatorDefault<double> {
    static bool compare(const double& p_lhs, const double& p_rhs)
    {
        return (p_lhs == p_rhs) || (::isnan(p_lhs) && ::isnan(p_rhs));
    }
};

template <>
struct HashMapComparatorDefault<Vector2> {
    static bool compare(const Vector2& p_lhs, const Vector2& p_rhs)
    {
        return ((p_lhs.x == p_rhs.x) || (::isnan(p_lhs.x) && ::isnan(p_rhs.x))) && ((p_lhs.y == p_rhs.y) || (::isnan(p_lhs.y) && ::isnan(p_rhs.y)));
    }
};

template <>
struct HashMapComparatorDefault<Vector3> {
    static bool compare(const Vector3& p_lhs, const Vector3& p_rhs)
    {
        return ((p_lhs.x == p_rhs.x) || (::isnan(p_lhs.x) && ::isnan(p_rhs.x))) && ((p_lhs.y == p_rhs.y) || (::isnan(p_lhs.y) && ::isnan(p_rhs.y))) && ((p_lhs.z == p_rhs.z) || (::isnan(p_lhs.z) && ::isnan(p_rhs.z)));
    }
};

constexpr uint32_t HASH_TABLE_SIZE_MAX = 29;

const uint32_t hash_table_size_primes[HASH_TABLE_SIZE_MAX] = {
    5,
    13,
    23,
    47,
    97,
    193,
    389,
    769,
    1543,
    3079,
    6151,
    12289,
    24593,
    49157,
    98317,
    196613,
    393241,
    786433,
    1572869,
    3145739,
    6291469,
    12582917,
    25165843,
    50331653,
    100663319,
    201326611,
    402653189,
    805306457,
    1610612741,
};

// Computed with elem_i = UINT64_C (0 x FFFFFFFF FFFFFFFF ) / d_i + 1, where d_i is the i-th element of the above array.
const uint64_t hash_table_size_primes_inv[HASH_TABLE_SIZE_MAX] = {
    3689348814741910324,
    1418980313362273202,
    802032351030850071,
    392483916461905354,
    190172619316593316,
    95578984837873325,
    47420935922132524,
    23987963684927896,
    11955116055547344,
    5991147799191151,
    2998982941588287,
    1501077717772769,
    750081082979285,
    375261795343686,
    187625172388393,
    93822606204624,
    46909513691883,
    23456218233098,
    11728086747027,
    5864041509391,
    2932024948977,
    1466014921160,
    733007198436,
    366503839517,
    183251896093,
    91625960335,
    45812983922,
    22906489714,
    11453246088
};

/**
 * Fastmod computes ( n mod d ) given the precomputed c much faster than n % d.
 * The implementation of fastmod is based on the following paper by Daniel Lemire et al.
 * Faster Remainder by Direct Computation: Applications to Compilers and Software Libraries
 * https://arxiv.org/abs/1902.01961
 */
static _FORCE_INLINE_ uint32_t fastmod(const uint32_t n, const uint64_t c, const uint32_t d)
{
#if defined(_MSC_VER)
        // Returns the upper 64 bits of the product of two 64-bit unsigned integers.
        // This intrinsic function is required since MSVC does not support unsigned 128-bit integers.
    #if defined(_M_X64) || defined(_M_ARM64)
    return static_cast<uint32_t>(__umulh(c * n, d));
    #else
    // Fallback to the slower method for 32-bit platforms.
    return n % d;
    #endif // _M_X64 || _M_ARM64
#else
    #ifdef __SIZEOF_INT128__
    // Prevent compiler warning, because we know what we are doing.
    uint64_t                                lowbits = c * n;
    __extension__ typedef unsigned __int128 uint128;
    return static_cast<uint64_t>(((uint128)lowbits * d) >> 64);
    #else
    // Fallback to the slower method if no 128-bit unsigned integer type is available.
    return n % d;
    #endif // __SIZEOF_INT128__
#endif     // _MSC_VER
}

} // namespace godot

#endif // HASHFUNCS_H
